I used to have a cast-iron signal cannon that length. It was configured to shoot shotgun shells though. Very interesting breech-loading configuration. I had gleaned that such items were used in holiday celebrations and to signal the start of races, or possibly as maritime signals. Shoulda never sold the thing; regret it every time i think about it.
Your piece looks like it may have some very respectable age to it. Splendid find. Way too big to be a mere toy.